Thin-layer electromagnetic absorber design

Musal, H. M.; Hahn, H.

doi:10.1109/20.42454

Cited by 187 publications

(74 citation statements)

References 3 publications

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“…The frequencies of interest in these measurements and calculations typically ranges from 0.1 − 20 GHz. At center frequencies of about 0.2-0.3 GHz, fractional bandwidths (below -20 dB re ectivity level) of 100-140% for a material thicknesses of a few mm is reported [13,22]. For center frequencies in the range 1 -20 GHz the bandwidth is usually smaller.…”

Section: Introductionmentioning

confidence: 99%

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Biased Magnetic Materials in Ram Applications

Ramprecht¹,

Sjöberg²

2007

PIER

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The magnetization of a ferro-or ferri-magnetic material has been modeled with the Landau-Lifshitz-Gilbert (LLG) equation. In this model demagnetization e ects are included. By applying a linearized small signal model of the LLG equation, it was found that the material can be described by an e ective permeability and with the aid of a static external biasing eld, the material can be switched between a Lorentz-like material and a material that exhibits a magnetic conductivity. Furthermore, the re ection coe cient for normally impinging waves on a PEC covered with a ferro/ferri-magnetic material, biased in the normal direction, is calculated. When the material is switched into the resonance mode, we found that there will be two distinct resonance frequencies in the re ection coe cient, one associated with the precession frequency of the magnetization and one associated with the thickness of the layer. The former of these resonance frequencies can be controlled by the bias eld and for a bias eld strength close to the saturation magnetization, where the material starts to exhibit a magnetic conductivity, one can achieve low re ection (around -20 dB) for a quite large bandwidth (more than two decades).

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Section: Introductionmentioning

confidence: 99%

“…Absorbers consisting of ferrite material have been manufactured and analyzed for some time [5,13,22,26]. Recently, composites with ferromagnetic-or ferrite inclusions in a background material have been considered as microwave absorbers [10,14,21,23,32].…”

Section: Introductionmentioning

confidence: 99%

Biased Magnetic Materials in Ram Applications

Ramprecht¹,

Sjöberg²

2007

PIER

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“…In resonant absorbers with a quarter wavelength, zero reflection can be obtained by impedance matching at the surface of the absorbing layer, which requires an appropriate combination of magnetic permeability and dielectric permittivity at a given thickness and frequency of interest [1,2]. Based on transmission line theory, the impedance matching can be obtained when the real part of the input impedance is equal to free space impedance (= 377 Ω) and the imaginary part is zero.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Microwave Absorbance of Polymer Composites of W-Type Hexaferrite Powders by Attachment of Frequency Selective Surface

Cho

Kim

2017

Archives of Metallurgy and Materials

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This work investigates the effect of a frequency selective surface (FSS) composed of a regular array of square loop elements on the absorption properties of grounded ferrite composites. Polymer matrix composites of CoZnW hexaferrite powders having small magnetic loss were used as the substrate material. Computational tools were used to model the interaction between electromagnetic waves and materials and determine the reflection coefficient. Reflection loss and bandwidth were greatly improved by attaching an FSS with controlled electrical resistance (R) onto the grounded ferrite composites. For the FSS with R = 800 Ω, the minimum reflection loss decreased to -25 dB at 10 GHz and the bandwidth was broadened to 7.5-12.5 GHz with respect to -10 dB reflection loss.

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“…Among these variables, the EM characteristics and the structural shape are set as design conditions, and the main design parameters are reduced to the permittivity, permeability, and thickness of the absorbing layers. RAS are usually designed to minimize the reflection coefficient, which is conventionally applied to the RAM [10][11][12][13][14][15]. The performance of the RAS-minimizing reflection coefficient is degraded when design results are applied to curved structures.…”

Section: Introductionmentioning

confidence: 99%

Design Optimization of Composite Radar Absorbing Structures to Improve Stealth Performance

Jang¹,

Kim²,

Park³

et al. 2016

International Journal of Aeronautical and Space Sciences

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In this study, an efficient method of designing laminate composite radar absorbing structures (RAS) is proposed with consideration given to the structural shape so as to improve aircraft stealth performance. The calculation of the radar cross section (RCS) should be decreased to enhance the efficiency of the stochastic optimization when designing an RAS. In the proposed method, RAS are optimized to match up the input impedance of the minimal RCS, which is obtained by using physical optics and the transmission line theory. Single and double layer dielectric RAS for aircraft wings are employed as numerical examples and designed using the proposed method, RCS minimization and reflection coefficient minimization. The availability of the proposed method is assessed by comparing the similarity of the results and computation time with other design methods. According to the results, the proposed method produces the same results as the stochastic optimization, which adopts the RCS as the objective function, and can improve RAS design efficiency by reducing the number of RCS analyses.

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Thin-layer electromagnetic absorber design

Cited by 187 publications

References 3 publications

Biased Magnetic Materials in Ram Applications

Biased Magnetic Materials in Ram Applications

Improvement of Microwave Absorbance of Polymer Composites of W-Type Hexaferrite Powders by Attachment of Frequency Selective Surface

Design Optimization of Composite Radar Absorbing Structures to Improve Stealth Performance

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